Answer:Increase by a factor of 25
Explanation:
We know that magnetic force is proportional to [tex]\frac{1}{r^2}[/tex]
where r is the distance between them
[tex]F\propto B\propto \frac{1}{r^2}[/tex]
Thus [tex]F\propto \frac{1}{r^2}[/tex]
Where [tex]B[/tex]=magnetic field
If distance is reduced by a factor of [tex]5[/tex] then force must increase by a factor of [tex]25[/tex] because
[tex]r\rightarrow \frac{r}{5}[/tex]
so [tex]F\propto \dfrac{1}{(\frac{r}{5})^2}[/tex]
[tex]F\propto \frac{25}{r^2}[/tex]
